Provided by: libpcap0.8_1.10.4-4_amd64 bug

NAME

       pcap-filter - packet filter syntax

DESCRIPTION

       pcap_compile(3PCAP)  is  used  to  compile  a string into a filter program.  The resulting
       filter program can then be applied to some stream of packets to  determine  which  packets
       will   be   supplied   to  pcap_loop(3PCAP),  pcap_dispatch(3PCAP),  pcap_next(3PCAP),  or
       pcap_next_ex(3PCAP).

       The filter expression consists of one or more primitives.  Primitives usually  consist  of
       an  id  (name  or  number)  preceded by one or more qualifiers.  There are three different
       kinds of qualifier:

       type   type qualifiers say what kind of thing the id name or number refers  to.   Possible
              types are host, net, port and portrange.  E.g., `host foo', `net 128.3', `port 20',
              `portrange 6000-6008'.  If there is no type qualifier, host is assumed.

       dir    dir qualifiers specify a particular transfer direction to and/or from id.  Possible
              directions  are src, dst, src or dst, src and dst, ra, ta, addr1, addr2, addr3, and
              addr4.  E.g., `src foo', `dst net 128.3', `src or dst port ftp-data'.  If there  is
              no  dir  qualifier,  `src or dst' is assumed.  The ra, ta, addr1, addr2, addr3, and
              addr4 qualifiers are only valid for IEEE 802.11 Wireless LAN link layers.

       proto  proto qualifiers restrict the match to a particular protocol.   Possible  protocols
              are:  ether,  fddi, tr, wlan, ip, ip6, arp, rarp, decnet, sctp, tcp and udp.  E.g.,
              `ether src foo', `arp net 128.3', `tcp port 21', `udp portrange  7000-7009',  `wlan
              addr2  0:2:3:4:5:6'.  If there is no proto qualifier, all protocols consistent with
              the type are assumed.  E.g., `src foo' means `(ip or arp or rarp)  src  foo',  `net
              bar'  means `(ip or arp or rarp) net bar' and `port 53' means `(tcp or udp or sctp)
              port 53' (note that these examples use invalid syntax to illustrate the principle).

       [fddi is actually an alias for ether; the parser treats them identically as meaning  ``the
       data link level used on the specified network interface''.  FDDI headers contain Ethernet-
       like source and destination addresses, and often contain Ethernet-like  packet  types,  so
       you  can  filter  on  these  FDDI fields just as with the analogous Ethernet fields.  FDDI
       headers also contain other fields, but  you  cannot  name  them  explicitly  in  a  filter
       expression.

       Similarly,  tr  and  wlan are aliases for ether; the previous paragraph's statements about
       FDDI headers also apply to Token  Ring  and  802.11  wireless  LAN  headers.   For  802.11
       headers,  the  destination address is the DA field and the source address is the SA field;
       the BSSID, RA, and TA fields aren't tested.]

       In addition to the above, there are some special `primitive' keywords  that  don't  follow
       the  pattern:  gateway, broadcast, less, greater and arithmetic expressions.  All of these
       are described below.

       More complex filter expressions are built up by using  the  words  and,  or  and  not  (or
       equivalently: `&&', `||' and `!' respectively) to combine primitives.  E.g., `host foo and
       not port ftp and not port ftp-data'.  To save typing, identical  qualifier  lists  can  be
       omitted.   E.g.,  `tcp dst port ftp or ftp-data or domain' is exactly the same as `tcp dst
       port ftp or tcp dst port ftp-data or tcp dst port domain'.

       Allowable primitives are:

       dst host hostnameaddr
              True if the IPv4/v6 destination field of the packet is hostnameaddr, which  may  be
              either an address or a name.

       src host hostnameaddr
              True if the IPv4/v6 source field of the packet is hostnameaddr.

       host hostnameaddr
              True if either the IPv4/v6 source or destination of the packet is hostnameaddr.

              Any  of  the  above  host  expressions can be prepended with the keywords, ip, arp,
              rarp, or ip6 as in:
                   ip host hostnameaddr
              which is equivalent to:
                   ether proto \ip and host hostnameaddr
              If hostnameaddr is a name with multiple IPv4/v6 addresses,  each  address  will  be
              checked for a match.

       ether dst ethernameaddr
              True  if  the  Ethernet destination address is ethernameaddr.  ethernameaddr may be
              either  a  name  from  /etc/ethers  or  a  numerical  MAC  address  of   the   form
              "xx:xx:xx:xx:xx:xx",  "xx.xx.xx.xx.xx.xx",  "xx-xx-xx-xx-xx-xx",  "xxxx.xxxx.xxxx",
              "xxxxxxxxxxxx", or various mixes of ':', '.', and '-', where  each  "x"  is  a  hex
              digit (0-9, a-f, or A-F).

       ether src ethernameaddr
              True if the Ethernet source address is ethernameaddr.

       ether host ethernameaddr
              True if either the Ethernet source or destination address is ethernameaddr.

       gateway host
              True  if  the  packet  used  host  as  a  gateway.   I.e.,  the  Ethernet source or
              destination address was host but neither the IP source nor the IP  destination  was
              host.  Host must be a name and must be found both by the machine's host-name-to-IP-
              address resolution mechanisms (host name file, DNS, NIS, etc.) and by the machine's
              host-name-to-Ethernet-address   resolution   mechanism  (/etc/ethers,  etc.).   (An
              equivalent expression is
                   ether host ethernameaddr and not host hostnameaddr
              which can be used with either names or numbers for hostnameaddr  /  ethernameaddr.)
              This syntax does not work in IPv6-enabled configuration at this moment.

       dst net netnameaddr
              True  if  the  IPv4/v6  destination  address  of the packet has a network number of
              netnameaddr.  Net may be either a name from the networks  database  (/etc/networks,
              etc.)  or a network number.  An IPv4 network number can be written as a dotted quad
              (e.g., 192.168.1.0), dotted triple (e.g., 192.168.1), dotted pair (e.g, 172.16), or
              single  number  (e.g., 10); the netmask is 255.255.255.255 for a dotted quad (which
              means  that  it's  really  a  host  match),  255.255.255.0  for  a  dotted  triple,
              255.255.0.0  for  a dotted pair, or 255.0.0.0 for a single number.  An IPv6 network
              number must be written out fully; the netmask is ff:ff:ff:ff:ff:ff:ff:ff,  so  IPv6
              "network"  matches  are  really always host matches, and a network match requires a
              netmask length.

       src net netnameaddr
              True if the  IPv4/v6  source  address  of  the  packet  has  a  network  number  of
              netnameaddr.

       net netnameaddr
              True  if  either  the  IPv4/v6  source  or  destination address of the packet has a
              network number of netnameaddr.

       net netaddr mask netmask
              True if the IPv4 address  matches  netaddr  with  the  specific  netmask.   May  be
              qualified with src or dst.  Note that this syntax is not valid for IPv6 netaddr.

       net netaddr/len
              True  if  the IPv4/v6 address matches netaddr with a netmask len bits wide.  May be
              qualified with src or dst.

       dst port portnamenum
              True if the packet is IPv4/v6 TCP, UDP or SCTP and has a destination port value  of
              portnamenum.   The portnamenum can be a number or a name used in /etc/services (see
              tcp(4P) and udp(4P)).  If a name is used, both the port  number  and  protocol  are
              checked.   If  a  number or ambiguous name is used, only the port number is checked
              (e.g., `dst port 513' will print both tcp/login traffic and  udp/who  traffic,  and
              `port domain' will print both tcp/domain and udp/domain traffic).

       src port portnamenum
              True if the packet has a source port value of portnamenum.

       port portnamenum
              True if either the source or destination port of the packet is portnamenum.

       dst portrange portnamenum1-portnamenum2
              True  if  the  packet  is IPv4/v6 TCP, UDP or SCTP and has a destination port value
              between  portnamenum1  and  portnamenum2  (both   inclusive).    portnamenum1   and
              portnamenum2  are  interpreted in the same fashion as the portnamenum parameter for
              port.

       src portrange portnamenum1-portnamenum2
              True if the packet has a source port value between  portnamenum1  and  portnamenum2
              (both inclusive).

       portrange portnamenum1-portnamenum2
              True if either the source or destination port of the packet is between portnamenum1
              and portnamenum2 (both inclusive).

              Any of the above port or port range expressions can be prepended with the keywords,
              tcp, udp or sctp, as in:
                   tcp src port portnamenum
              which matches only TCP packets whose source port is portnamenum.

       less length
              True  if  the packet has a length less than or equal to length.  This is equivalent
              to:
                   len <= length

       greater length
              True if the packet has  a  length  greater  than  or  equal  to  length.   This  is
              equivalent to:
                   len >= length

       ip proto protocol
              True  if  the  packet  is  an  IPv4  packet (see ip(4P)) of protocol type protocol.
              Protocol can be a number or one of the names recognized by getprotobyname(3) (as in
              e.g.  `getent(1)  protocols'),  typically  from  an  entry  in  /etc/protocols, for
              example: ah, esp, eigrp (only in Linux, FreeBSD, NetBSD, DragonFly BSD, and macOS),
              icmp, igmp, igrp (only in OpenBSD), pim, sctp, tcp, udp or vrrp.  Note that most of
              these example identifiers are also keywords and must be escaped via backslash  (\).
              Note that this primitive does not chase the protocol header chain.

       icmp   Abbreviation for:
                   ip proto 1

       ip6 proto protocol
              True  if  the  packet is an IPv6 packet of protocol type protocol.  (See `ip proto'
              above for the meaning of protocol.)  Note that the IPv6  variant  of  ICMP  uses  a
              different  protocol number, named ipv6-icmp in AIX, FreeBSD, illumos, Linux, macOS,
              NetBSD, OpenBSD, Solaris and Windows.  Note that this primitive does not chase  the
              protocol header chain.

       icmp6  Abbreviation for:
                   ip6 proto 58

       proto protocol
              True  if  the packet is an IPv4 or IPv6 packet of protocol type protocol.  (See `ip
              proto' above for the meaning of protocol.)  Note that this primitive does not chase
              the protocol header chain.

       ah, esp, pim, sctp, tcp, udp
              Abbreviations for:
                   proto \protocol
              where protocol is one of the above protocols.

       ip6 protochain protocol
              True  if the packet is IPv6 packet, and contains protocol header with type protocol
              in its protocol header chain.  (See `ip proto' above for the meaning of  protocol.)
              For example,
                   ip6 protochain 6
              matches any IPv6 packet with TCP protocol header in the protocol header chain.  The
              packet may contain, for example, authentication header, routing header, or  hop-by-
              hop  option  header,  between  IPv6 header and TCP header.  The BPF code emitted by
              this primitive is complex and cannot be optimized by the BPF optimizer code, and is
              not  supported  by  filter engines in the kernel, so this can be somewhat slow, and
              may cause more packets to be dropped.

       ip protochain protocol
              Equivalent to ip6 protochain protocol, but this is for IPv4.  (See `ip proto' above
              for the meaning of protocol.)

       protochain protocol
              True  if  the packet is an IPv4 or IPv6 packet of protocol type protocol.  (See `ip
              proto' above for the meaning of protocol.)  Note that  this  primitive  chases  the
              protocol header chain.

       ether broadcast
              True if the packet is an Ethernet broadcast packet.  The ether keyword is optional.

       ip broadcast
              True  if the packet is an IPv4 broadcast packet.  It checks for both the all-zeroes
              and all-ones broadcast conventions, and looks up the subnet mask on  the  interface
              on which the capture is being done.

              If  the  subnet  mask  of  the  interface on which the capture is being done is not
              available, either because the interface on which  capture  is  being  done  has  no
              netmask  or  because  the capture is being done on the Linux "any" interface, which
              can capture on more than one interface, this check will not work correctly.

       ether multicast
              True if the packet is an Ethernet multicast packet.  The ether keyword is optional.
              This is shorthand for `ether[0] & 1 != 0'.

       ip multicast
              True if the packet is an IPv4 multicast packet.

       ip6 multicast
              True if the packet is an IPv6 multicast packet.

       ether proto protocol
              True  if  the packet is of ether type protocol.  Protocol can be a number or one of
              the names aarp, arp, atalk, decnet, ip, ip6, ipx, iso, lat, loopback, mopdl, moprc,
              netbeui,  rarp,  sca  or  stp.   Note  these identifiers (except loopback) are also
              keywords and must be escaped via backslash (\).

              [In the case of FDDI (e.g., `fddi proto \arp'), Token Ring (e.g., `tr proto \arp'),
              and  IEEE  802.11  wireless  LANs  (e.g.,  `wlan  proto  \arp'),  for most of those
              protocols, the protocol identification comes from the 802.2  Logical  Link  Control
              (LLC)  header,  which  is usually layered on top of the FDDI, Token Ring, or 802.11
              header.

              When filtering for most protocol identifiers on FDDI, Token Ring,  or  802.11,  the
              filter  checks only the protocol ID field of an LLC header in so-called SNAP format
              with  an  Organizational  Unit  Identifier  (OUI)  of  0x000000,  for  encapsulated
              Ethernet;  it  doesn't  check  whether  the packet is in SNAP format with an OUI of
              0x000000.  The exceptions are:

              iso    the filter checks the DSAP  (Destination  Service  Access  Point)  and  SSAP
                     (Source Service Access Point) fields of the LLC header;

              stp and netbeui
                     the filter checks the DSAP of the LLC header;

              atalk  the  filter  checks for a SNAP-format packet with an OUI of 0x080007 and the
                     AppleTalk etype.

              In the case of Ethernet, the filter checks the Ethernet  type  field  for  most  of
              those protocols.  The exceptions are:

              iso, stp, and netbeui
                     the  filter  checks  for an 802.3 frame and then checks the LLC header as it
                     does for FDDI, Token Ring, and 802.11;

              atalk  the filter checks both for the AppleTalk etype in an Ethernet frame and  for
                     a SNAP-format packet as it does for FDDI, Token Ring, and 802.11;

              aarp   the filter checks for the AppleTalk ARP etype in either an Ethernet frame or
                     an 802.2 SNAP frame with an OUI of 0x000000;

              ipx    the filter checks for the IPX etype in an Ethernet frame, the  IPX  DSAP  in
                     the  LLC  header, the 802.3-with-no-LLC-header encapsulation of IPX, and the
                     IPX etype in a SNAP frame.

       ip, ip6, arp, rarp, atalk, aarp, decnet, iso, stp, ipx, netbeui
              Abbreviations for:
                   ether proto \protocol
              where protocol is one of the above protocols.

       lat, moprc, mopdl
              Abbreviations for:
                   ether proto \protocol
              where protocol is one of the above protocols.  Note that not all applications using
              pcap(3PCAP) currently know how to parse these protocols.

       decnet src decnetaddr
              True  if  the  DECnet  source address is decnetaddr, which may be an address of the
              form ``10.123'', or a  DECnet  host  name.   [DECnet  host  name  support  is  only
              available on ULTRIX systems that are configured to run DECnet.]

       decnet dst decnetaddr
              True if the DECnet destination address is decnetaddr.

       decnet host decnetaddr
              True if either the DECnet source or destination address is decnetaddr.

       llc    True if the packet has an 802.2 LLC header.  This includes:

              Ethernet  packets  with  a  length  field  rather than a type field that aren't raw
              NetWare-over-802.3 packets;

              IEEE 802.11 data packets;

              Token Ring packets (no check is done for LLC frames);

              FDDI packets (no check is done for LLC frames);

              LLC-encapsulated ATM packets, for SunATM on Solaris.

       llc type
              True if the packet has an 802.2 LLC header and has the specified type.  type can be
              one of:

              i      Information (I) PDUs

              s      Supervisory (S) PDUs

              u      Unnumbered (U) PDUs

              rr     Receiver Ready (RR) S PDUs

              rnr    Receiver Not Ready (RNR) S PDUs

              rej    Reject (REJ) S PDUs

              ui     Unnumbered Information (UI) U PDUs

              ua     Unnumbered Acknowledgment (UA) U PDUs

              disc   Disconnect (DISC) U PDUs

              sabme  Set Asynchronous Balanced Mode Extended (SABME) U PDUs

              test   Test (TEST) U PDUs

              xid    Exchange Identification (XID) U PDUs

              frmr   Frame Reject (FRMR) U PDUs

       inbound
              Packet  was  received  by the host performing the capture rather than being sent by
              that host.  This is only supported for certain link-layer types, such as  SLIP  and
              the  ``cooked''  Linux  capture mode used for the ``any'' device and for some other
              device types.

       outbound
              Packet was sent by the host performing the capture rather than  being  received  by
              that  host.   This is only supported for certain link-layer types, such as SLIP and
              the ``cooked'' Linux capture mode used for the ``any'' device and  for  some  other
              device types.

       ifname interface
              True  if the packet was logged as coming from the specified interface (applies only
              to packets logged by OpenBSD's or FreeBSD's pf(4)).

       on interface
              Synonymous with the ifname modifier.

       rnr num
              True if the packet was logged as matching the specified  PF  rule  number  (applies
              only to packets logged by OpenBSD's or FreeBSD's pf(4)).

       rulenum num
              Synonymous with the rnr modifier.

       reason code
              True  if  the packet was logged with the specified PF reason code.  The known codes
              are: match, bad-offset, fragment, short, normalize, and  memory  (applies  only  to
              packets logged by OpenBSD's or FreeBSD's pf(4)).

       rset name
              True  if  the  packet  was  logged  as matching the specified PF ruleset name of an
              anchored ruleset (applies only to packets logged by OpenBSD's or FreeBSD's pf(4)).

       ruleset name
              Synonymous with the rset modifier.

       srnr num
              True if the packet was logged as matching  the  specified  PF  rule  number  of  an
              anchored ruleset (applies only to packets logged by OpenBSD's or FreeBSD's pf(4)).

       subrulenum num
              Synonymous with the srnr modifier.

       action act
              True  if  PF  took  the specified action when the packet was logged.  Known actions
              are: pass and block and, with later versions of pf(4), nat, rdr,  binat  and  scrub
              (applies only to packets logged by OpenBSD's or FreeBSD's pf(4)).

       wlan ra ehost
              True if the IEEE 802.11 RA is ehost.  The RA field is used in all frames except for
              management frames.

       wlan ta ehost
              True if the IEEE 802.11 TA is ehost.  The TA field is used in all frames except for
              management frames and CTS (Clear To Send) and ACK (Acknowledgment) control frames.

       wlan addr1 ehost
              True if the first IEEE 802.11 address is ehost.

       wlan addr2 ehost
              True  if  the second IEEE 802.11 address, if present, is ehost.  The second address
              field is used in all frames except for CTS (Clear To Send) and ACK (Acknowledgment)
              control frames.

       wlan addr3 ehost
              True  if  the  third  IEEE 802.11 address, if present, is ehost.  The third address
              field is used in management and data frames, but not in control frames.

       wlan addr4 ehost
              True if the fourth IEEE 802.11 address, if present, is ehost.  The  fourth  address
              field is only used for WDS (Wireless Distribution System) frames.

       type wlan_type
              True  if  the  IEEE  802.11  frame  type  matches  the  specified wlan_type.  Valid
              wlan_types are: mgt, ctl and data.

       type wlan_type subtype wlan_subtype
              True if the IEEE 802.11 frame  type  matches  the  specified  wlan_type  and  frame
              subtype matches the specified wlan_subtype.

              If  the specified wlan_type is mgt, then valid wlan_subtypes are: assoc-req, assoc-
              resp, reassoc-req, reassoc-resp, probe-req,  probe-resp,  beacon,  atim,  disassoc,
              auth and deauth.

              If the specified wlan_type is ctl, then valid wlan_subtypes are: ps-poll, rts, cts,
              ack, cf-end and cf-end-ack.

              If  the  specified  wlan_type  is  data,  then  valid  wlan_subtypes   are:   data,
              data-cf-ack,  data-cf-poll,  data-cf-ack-poll,  null, cf-ack, cf-poll, cf-ack-poll,
              qos-data, qos-data-cf-ack, qos-data-cf-poll, qos-data-cf-ack-poll, qos, qos-cf-poll
              and qos-cf-ack-poll.

       subtype wlan_subtype
              True  if the IEEE 802.11 frame subtype matches the specified wlan_subtype and frame
              has the type to which the specified wlan_subtype belongs.

       dir direction
              True if the IEEE 802.11 frame direction matches  the  specified  direction.   Valid
              directions are: nods, tods, fromds, dstods, or a numeric value.

       vlan [vlan_id]
              True  if  the  packet  is  an  IEEE 802.1Q VLAN packet.  If the optional vlan_id is
              specified, only true if the packet has the specified vlan_id.  Note that the  first
              vlan  keyword  encountered  in  an  expression changes the decoding offsets for the
              remainder of the expression on the assumption that the packet  is  a  VLAN  packet.
              The  `vlan  [vlan_id]`  keyword  may  be  used  more  than  once, to filter on VLAN
              hierarchies.  Each use of that keyword increments the filter offsets by 4.

              For example:
                   vlan 100 && vlan 200
              filters on VLAN 200 encapsulated within VLAN 100, and
                   vlan && vlan 300 && ip
              filters IPv4 protocol encapsulated in VLAN 300 encapsulated within any higher order
              VLAN.

       mpls [label_num]
              True if the packet is an MPLS packet.  If the optional label_num is specified, only
              true if the packet has the specified label_num.  Note that the first  mpls  keyword
              encountered  in an expression changes the decoding offsets for the remainder of the
              expression on the assumption that the packet is a MPLS-encapsulated IP packet.  The
              `mpls  [label_num]`  keyword  may  be  used  more  than  once,  to  filter  on MPLS
              hierarchies.  Each use of that keyword increments the filter offsets by 4.

              For example:
                   mpls 100000 && mpls 1024
              filters packets with an outer label of 100000 and an inner label of 1024, and
                   mpls && mpls 1024 && host 192.9.200.1
              filters packets to or from 192.9.200.1 with an inner label of 1024  and  any  outer
              label.

       pppoed True if the packet is a PPP-over-Ethernet Discovery packet (Ethernet type 0x8863).

       pppoes [session_id]
              True  if  the  packet is a PPP-over-Ethernet Session packet (Ethernet type 0x8864).
              If the optional session_id is specified, only true if the packet has the  specified
              session_id.   Note  that  the  first  pppoes  keyword  encountered in an expression
              changes the decoding offsets for the remainder of the expression on the  assumption
              that the packet is a PPPoE session packet.

              For example:
                   pppoes 0x27 && ip
              filters IPv4 protocol encapsulated in PPPoE session id 0x27.

       geneve [vni]
              True  if  the  packet  is  a  Geneve packet (UDP port 6081). If the optional vni is
              specified, only true if the packet has the  specified  vni.   Note  that  when  the
              geneve keyword is encountered in an expression, it changes the decoding offsets for
              the remainder of the expression on the assumption  that  the  packet  is  a  Geneve
              packet.

              For example:
                   geneve 0xb && ip
              filters  IPv4  protocol  encapsulated  in Geneve with VNI 0xb. This will match both
              IPv4 directly encapsulated in Geneve as well as IPv4 contained inside  an  Ethernet
              frame.

       iso proto protocol
              True  if  the packet is an OSI packet of protocol type protocol.  Protocol can be a
              number or one of the names clnp, esis, or isis.

       clnp, esis, isis
              Abbreviations for:
                   iso proto \protocol
              where protocol is one of the above protocols.

       l1, l2, iih, lsp, snp, csnp, psnp
              Abbreviations for IS-IS PDU types.

       vpi n  True if the packet is an ATM packet, for SunATM on Solaris,  with  a  virtual  path
              identifier of n.

       vci n  True  if the packet is an ATM packet, for SunATM on Solaris, with a virtual channel
              identifier of n.

       lane   True if the packet is an ATM packet, for SunATM on Solaris,  and  is  an  ATM  LANE
              packet.   Note that the first lane keyword encountered in an expression changes the
              tests done in the remainder of the expression on the assumption that the packet  is
              either  a LANE emulated Ethernet packet or a LANE LE Control packet.  If lane isn't
              specified, the tests are done under the assumption  that  the  packet  is  an  LLC-
              encapsulated packet.

       oamf4s True if the packet is an ATM packet, for SunATM on Solaris, and is a segment OAM F4
              flow cell (VPI=0 & VCI=3).

       oamf4e True if the packet is an ATM packet, for SunATM on Solaris, and  is  an  end-to-end
              OAM F4 flow cell (VPI=0 & VCI=4).

       oamf4  True  if  the  packet  is an ATM packet, for SunATM on Solaris, and is a segment or
              end-to-end OAM F4 flow cell (VPI=0 & (VCI=3 | VCI=4)).

       oam    True if the packet is an ATM packet, for SunATM on Solaris, and  is  a  segment  or
              end-to-end OAM F4 flow cell (VPI=0 & (VCI=3 | VCI=4)).

       metac  True  if  the  packet  is  an  ATM  packet, for SunATM on Solaris, and is on a meta
              signaling circuit (VPI=0 & VCI=1).

       bcc    True if the packet is an ATM packet, for SunATM on Solaris, and is on  a  broadcast
              signaling circuit (VPI=0 & VCI=2).

       sc     True  if  the packet is an ATM packet, for SunATM on Solaris, and is on a signaling
              circuit (VPI=0 & VCI=5).

       ilmic  True if the packet is an ATM packet, for SunATM on  Solaris,  and  is  on  an  ILMI
              circuit (VPI=0 & VCI=16).

       connectmsg
              True  if  the packet is an ATM packet, for SunATM on Solaris, and is on a signaling
              circuit and is a Q.2931 Setup, Call Proceeding, Connect, Connect Ack,  Release,  or
              Release Done message.

       metaconnect
              True  if  the  packet  is  an  ATM  packet, for SunATM on Solaris, and is on a meta
              signaling circuit and is a Q.2931 Setup,  Call  Proceeding,  Connect,  Release,  or
              Release Done message.

       expr1 relop expr2
              True  if  the  relation  holds.  Relop is one of {>, <, >=, <=, =, ==, !=} (where =
              means the same as ==).  Each  of  expr1  and  expr2  is  an  arithmetic  expression
              composed  of  integer constants (expressed in standard C syntax), the normal binary
              operators {+, -, *, /, %, &, |, ^, <<, >>}, a length operator, and  special  packet
              data  accessors.   Note  that  all  comparisons are unsigned, so that, for example,
              0x80000000 and 0xffffffff are > 0.

              The % and ^ operators are currently only supported for filtering in the  kernel  on
              particular  operating  systems  (for  example:  FreeBSD,  Linux  with 3.7 and later
              kernels, NetBSD); on  all  other  systems  (for  example:  AIX,  illumos,  Solaris,
              OpenBSD),  if  those operators are used, filtering will be done in user mode, which
              will increase the overhead of capturing packets and may cause more  packets  to  be
              dropped.

              The length operator, indicated by the keyword len, gives the length of the packet.

              To access data inside the packet, use the following syntax:
                   proto [ expr : size ]
              Proto is one of arp, atalk, carp, decnet, ether, fddi, icmp, icmp6, igmp, igrp, ip,
              ip6, lat, link, mopdl, moprc, pim, ppp, radio, rarp, sca, sctp, slip, tcp, tr, udp,
              vrrp  or  wlan,  and indicates the protocol layer for the index operation.  (ether,
              fddi, link, ppp, slip, tr and wlan all refer to the link layer. radio refers to the
              "radio header" added to some 802.11 captures.)  Note that tcp, udp and other upper-
              layer protocol types only apply to IPv4, not  IPv6  (this  will  be  fixed  in  the
              future).   The  byte  offset, relative to the indicated protocol layer, is given by
              expr.  Size is optional and indicates the number of bytes in the field of interest;
              it can be either one, two, or four, and defaults to one.

              For  example,  `ether[0]  &  1 != 0' catches all multicast traffic.  The expression
              `ip[0] & 0xf != 5' catches all IPv4 packets with options.  The expression  `ip[6:2]
              &  0x1fff = 0' catches only unfragmented IPv4 datagrams and frag zero of fragmented
              IPv4 datagrams.  This check  is  implicitly  applied  to  the  tcp  and  udp  index
              operations.   For  instance,  tcp[0] always means the first byte of the TCP header,
              and never means the first byte of an intervening fragment.

              Some offsets and field values may be expressed as  names  rather  than  as  numeric
              values.   The following protocol header field offsets are available: icmptype (ICMP
              type field), icmp6type (ICMPv6 type field), icmpcode (ICMP code  field),  icmp6code
              (ICMPv6 code field) and tcpflags (TCP flags field).

              The  following  ICMP type field values are available: icmp-echoreply, icmp-unreach,
              icmp-sourcequench, icmp-redirect, icmp-echo, icmp-routeradvert, icmp-routersolicit,
              icmp-timxceed,    icmp-paramprob,    icmp-tstamp,    icmp-tstampreply,   icmp-ireq,
              icmp-ireqreply, icmp-maskreq, icmp-maskreply.

              The following ICMPv6 type field  values  are  available:  icmp6-destinationunreach,
              icmp6-packettoobig,    icmp6-timeexceeded,    icmp6-parameterproblem,   icmp6-echo,
              icmp6-echoreply,   icmp6-multicastlistenerquery,   icmp6-multicastlistenerreportv1,
              icmp6-multicastlistenerdone,        icmp6-routersolicit,        icmp6-routeradvert,
              icmp6-neighborsolicit,  icmp6-neighboradvert,  icmp6-redirect,   icmp6-routerrenum,
              icmp6-nodeinformationquery,                          icmp6-nodeinformationresponse,
              icmp6-ineighbordiscoverysolicit,                    icmp6-ineighbordiscoveryadvert,
              icmp6-multicastlistenerreportv2,                   icmp6-homeagentdiscoveryrequest,
              icmp6-homeagentdiscoveryreply, icmp6-mobileprefixsolicit, icmp6-mobileprefixadvert,
              icmp6-certpathsolicit,      icmp6-certpathadvert,      icmp6-multicastrouteradvert,
              icmp6-multicastroutersolicit, icmp6-multicastrouterterm.

              The following TCP flags field values are available: tcp-fin, tcp-syn, tcp-rst, tcp-
              push, tcp-ack, tcp-urg, tcp-ece, tcp-cwr.

       Primitives may be combined using:

              A parenthesized group of primitives and operators.

              Negation (`!' or `not').

              Concatenation (`&&' or `and').

              Alternation (`||' or `or').

       Negation  has the highest precedence.  Alternation and concatenation have equal precedence
       and associate left to right.  Note that explicit and tokens, not  juxtaposition,  are  now
       required for concatenation.

       If  an  identifier  is  given  without a keyword, the most recent keyword is assumed.  For
       example,
            not host vs and ace
       is short for
            not host vs and host ace
       which should not be confused with
            not (host vs or ace)

EXAMPLES

       To select all packets arriving at or departing from `sundown':
              host sundown

       To select traffic between `helios' and either `hot' or `ace':
              host helios and (hot or ace)

       To select all IPv4 packets between `ace' and any host except `helios':
              ip host ace and not helios

       To select all traffic between local hosts and hosts at Berkeley:
              net ucb-ether

       To select all FTP traffic through Internet gateway `snup':
              gateway snup and (port ftp or ftp-data)

       To select IPv4 traffic neither sourced from nor destined for local hosts (if  you  gateway
       to one other net, this stuff should never make it onto your local net).
              ip and not net localnet

       To  select  the  start  and end packets (the SYN and FIN packets) of each TCP conversation
       that involves a non-local host.
              tcp[tcpflags] & (tcp-syn|tcp-fin) != 0 and not src and dst net localnet

       To select the TCP packets with flags RST and ACK both set.  (i.e. select only the RST  and
       ACK flags in the flags field, and if the result is "RST and ACK both set", match)
              tcp[tcpflags] & (tcp-rst|tcp-ack) == (tcp-rst|tcp-ack)

       To  select all IPv4 HTTP packets to and from port 80, i.e. print only packets that contain
       data, not, for example, SYN and FIN packets and ACK-only packets.  (IPv6  is  left  as  an
       exercise for the reader.)
              tcp port 80 and (((ip[2:2] - ((ip[0]&0xf)<<2)) - ((tcp[12]&0xf0)>>2)) != 0)

       To select IPv4 packets longer than 576 bytes sent through gateway `snup':
              gateway snup and ip[2:2] > 576

       To select IPv4 broadcast or multicast packets that were not sent via Ethernet broadcast or
       multicast:
              ether[0] & 1 = 0 and ip[16] >= 224

       To select all ICMP packets that are not echo requests/replies (i.e., not ping packets):
              icmp[icmptype] != icmp-echo and icmp[icmptype] != icmp-echoreply
              icmp6[icmp6type] != icmp6-echo and icmp6[icmp6type] != icmp6-echoreply

BACKWARD COMPATIBILITY

       The ICMPv6 type code names, as well as the tcp-ece  and  tcp-cwr  TCP  flag  names  became
       available in libpcap 1.9.0.

       The geneve keyword became available in libpcap 1.8.0.

SEE ALSO

       pcap(3PCAP)

BUGS

       To report a security issue please send an e-mail to security@tcpdump.org.

       To  report bugs and other problems, contribute patches, request a feature, provide generic
       feedback etc please see the file CONTRIBUTING.md in the libpcap source tree root.

       Filter expressions on fields other than those in Token Ring  headers  will  not  correctly
       handle source-routed Token Ring packets.

       Filter  expressions on fields other than those in 802.11 headers will not correctly handle
       802.11 data packets with both To DS and From DS set.

       `ip6 proto' should chase header chain, but at this moment it does not.   `ip6  protochain'
       is supplied for this behavior.  For example, to match IPv6 fragments: `ip6 protochain 44'

       Arithmetic  expression against transport layer headers, like tcp[0], does not work against
       IPv6 packets.  It only looks at IPv4 packets.

                                         19 November 2022                          PCAP-FILTER(7)